Discoveries of planets around distant stars have become almost routine. But finding seven exoplanets in one go is something special. In February, a team of planet seekers announced that a small, cool star some 39 light-years away, TRAPPIST-1, hosts the most Earth-sized exoplanets yet found in one place: seven roughly Earth-sized worlds, at least three of which might host liquid water (SN...

Earth may not provide the best blueprint for how rocky planets are born.

An analysis of planets outside the solar system suggests that most hot, rocky exoplanets started out more like gassy Neptunes. Such planets are rocky now because their stars blew their thick atmospheres away, leaving nothing but an inhospitable core, researchers report in a paper posted online October 15 at arXiv....

By early next spring, astronomer David Kipping hopes to know if the object he’s spent his early career searching for is really there.

An astronomer at Columbia University, Kipping is perhaps most known for a project sifting through data from the Kepler space telescope on more than a thousand planets orbiting distant stars. But he’s more...

Astronomers estimate that wandering Jupiter-mass planets without a parent star are about a tenth as common as once believed, Ashley Yeager reported in “Giant solo planets are in limited supply” (SN: 8/19/17, p. 10).

Online reader Brian Bixby wondered how often such a rogue planet would come close to our solar system and proposed that one near the Kuiper Belt or Oort cloud...

Alien megastructures are out. The unusual fading of an oddball star is more likely caused by either clouds of dust or an abnormal cycle of brightening and dimming, two new papers suggest.

Huan Meng of the University of Arizona in Tucson and his colleagues suggest that KIC 8462852, known as Tabby’s star, is dimming thanks to an orbiting cloud of fine dust particles. The team observed the...

The moon had a magnetic field for at least 2 billion years, or maybe longer.

Analysis of a relatively young rock collected by Apollo astronauts reveals the moon had a weak magnetic field until 1 billion to 2.5 billion years ago, at least a billion years later than previous data showed. Extending this lifetime offers insights into how small bodies generate magnetic fields, researchers...

The first evidence for an exomoon — a moon orbiting a planet orbiting a distant star — may have been spotted in data from the Kepler space telescope. But surprisingly, exomoons in general may be rare, at least around planets close to their stars.

Alex Teachey and David Kipping of Columbia University analyzed the dips in light from exoplanets passing, or transiting, in front of their...

The infant moon may have had a thick metal atmosphere, where supersonic winds raised waves in its magma ocean.

That’s the conclusion of a new simulation that calculates how heat from the young sun, the Earth and the moon’s own hot surface could have vaporized lunar metals to give the moon an atmosphere as thick as Mars’. The model, reported online June 22 at arXiv.org, offers a way to...

Small worlds come in two flavors. The complete dataset from the original mission of the planet-hunting Kepler space telescope reveals a split in the exoplanet family tree, setting super-Earths apart from mini-Neptunes.

Kepler's final exoplanet catalog, released in a news conference June 19, now consists of 4,034 exoplanet candidates. Of those, 49 are rocky worlds in their stars'...